It depends also on the artist who is in charge of the animation. Jabba was done by Mark Dippe (who was later Banned from the Ranch). His work on the SE was pretty much redone in the later versions on DVD.

As for the Dewbacks, they are walking slowly across the screen in bright daylight and its a completely fictional creature The level of realism that is required for such a shot just wasn't possible in 97. If you compare that to CG shots in Jurassic Park, you have either running shots (the gallamimus) where your looking at a blur basically and a Brontosaurus who is just standing there and eating. So the shots in SE were more difficult creature wise.